Analysis of the changes of stromal precursor cell numbers in the thymus and the spleen of animals of different age groups

The objective of this study was to analyze the species differences in the numbers of stromal precursor cell (CFU-f), their cloning efficiency (CFE-0 and their dynamics in different organs during aging, using the mathematical gradient decrease method. Age changes of CFU-f numbers and of their CFE-f were studied in the thymus and the spleen of mice and guinea pigs. The study was performed using CFU-f cloning in monolayer cultures. CFU-f numbers and CFE-f were found to decrease with aging both in the thymus and the spleen of mice and guinea pigs. However these changes were different in each species and were variable in different organs of the animals of the same species, which, probably was associated with the physiological characteristics and aging peculiarities of the animals of different species and with the functional role of organs studied. The process of reduction was more significant in the thymus of guinea pigs and mice - the numbers of CFU-f were decreased 75- and 12-fold, respectively. Since it is known that the population of CFU-f in the thymus and the spleen includes inducible osteogenic precursor cells, the data obtained indicate the possibility of a reduction in numbers of this category ofstromal precursors, that could be one of the reasons of osteoporosis of aging. The application of a mathematical analysis using the gradient decrease method allows to predict the time-course of age changes and to evaluate the dynamics of CFU-f numbers and of CFE-f in association with organism aging.